Dark Pictures in Auto setting

I had the same problem before. Did you check to make sure your exposure compensation wasn't set at a negative number? half press the shutter and rotate the large dial on the back of the camera to change the exposure to 0. If this just changes your auto focus points, you have to change your custom function 13 from a value of 2 to 0 and then try half pressing the shutter and rotating the large dial in the back again. This fixed my problem with shooting in P mode (which I only used when absolutely necessary) and I hope it helps you.